Wolbachia is a bacterium that forms intracellular, inherited infections in insects, crustaceans, and other invertebrates, including nematodes such as Dirofilaria immitis, Onchocerca volvulus and Brugia malayi. The bacteria reside in cytoplasmic vacuoles and appear to be necessary for development, reproduction and long-term survival of nematodes. Wolbachia appear to play an important role in inflammatory pathogenesis of lymphatic filariasis.
Onchoceriasis (river blindness) is caused by the filarial nematode Onchocerca volvulus. Manifestations of onchoceriasis result primarily form the intense inflammatory reaction to Wolbachia, which emerges from microfilaria in the eye. The use of doxycycline to kill Wolbachia can cause sterility in adult worms.